lxc: bump to version 1.0.4

Also switch to new homepage and github download, and specify distro
variant since host distro != target distro and sample configs for each
case aren't useful anyway.
It sometimes failed to autodetect because some of the tests can't be
executed when cross compiling (happened on gentoo host).

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>